Endosseous Dental Implant

ABSTRACT

Dental implant, comprising a central body ( 1 ) with a substantially conical or frustoconical shape and having, extending from the end with a larger cross-section, a connection seat ( 701 ) able to receive a stump pin; this central body ( 1 ) is provided with a blade ( 2 ) positioned in a longitudinal mid-plane of said central body ( 1 ) and has a length so as to protrude beyond the end of said central body ( 1 ) which has a smaller cross-section; said central body ( 1 ) and said blade ( 2 ) are able to give the implant a substantially wedge-like form able to expand the bone during insertion.

The present invention relates to dental implants.

As is known, when performing dental implants, pins are fixed onto thejaw or onto the upper jaw bone of the patient in predeterminedpositions. These implants are also provided at the top with a seatinside which stump pins or the like are fixed. There are cases where thethickness of the patient's bone in which the implant is to be performedis very small, for example from 2.5 mm to 6 mm, and in such casesinsertion of the implant is very difficult since, in order to be able toinsert the implant, it is required to perform complicated regenerativesurgery using special bone grafts. Usually, a normal implant, which hasa main body with a cylindrical cross-section, requires a thickness ofthe bone crest at least 2 mm greater than its diameter.

The object of the present invention is therefore to provide a dentalimplant which may be advantageously applied even in small-thicknesszones of the bone crest of the patient, has limited volumetricdimensions, provides optimum anchoring in the bone, has a surface areasimilar to that of standard-size implants and ensures an excellentprimary stability.

This object is achieved by the present invention by means of a dentalimplant, characterized in that it comprises a central body with asubstantially conical or frustoconical shape and having, extending fromthe end with a larger cross-section, a connection seat able to receive astump pin; this central body is provided with a blade positioned in alongitudinal mid-plane of said central body and having a length such asto protrude beyond the end of said central body which has a smallercross-section; said central body, which is extremely thin also in thecoronal part, and said blade are able to give the implant asubstantially wedge-like form.

According to a further aspect of the present invention the presentdental implant comprises at least on the front or rear surface of saidcentral body and said blade at least one longitudinal guide ribprojecting from said surface.

According to yet another aspect of the present invention said centralbody and said blade have an angle of conicity of about 1° or less so asto give the implant a substantially blade-like form.

The presence of the longitudinal rib and the substantially blade-likeform of the present implant allow the latter to be inserted more easilyand more precisely inside the patient's bone since this insertion stepis performed along a predetermined insertion axis which is alwaysmaintained, without undesirable transverse displacements. The implantthus has an even greater primary stability, allowing perfect anchoringwhich prevents possible transverse movements. The substantiallyblade-like form ensures, moreover, even more efficient and simpleinsertion of said implant in bone zones with a small bone volume or inzones with atrophic crests. This rapid and simple insertion of thepresent implant decreases advantageously the surgery time, reducingtherefore the risk of infection and bone trauma. Differently from thepreceding implants with a blade-like form, this implant has the functionof expanding the bone during insertion and has a width and volume whichlie within the normal dimensions of a standard implant and each of theseimplants may therefore replace a single tooth.

Further objects and advantages of the present invention will beunderstood more clearly during the course of the following descriptionwhich is provided by way of a non-limiting example with reference to theaccompanying drawings in which:

FIG. 1 shows a front view of a first embodiment of a dental implantaccording to the present invention;

FIG. 2 shows a top plan view of the dental implant according to FIG. 1;

FIG. 3 shows a cross-sectional view along the line III-III of FIG. 2;

FIG. 4 shows a front view of a second embodiment of the dental implantaccording to the present invention; and

FIG. 5 shows a cross-sectional view along the line V-V of FIG. 4.

With reference to the accompanying drawings and with particularreference to FIG. 1 thereof, 1 denotes the central body, with asubstantially conical or frustoconical shape, of the present dentalimplant according to a first embodiment of the invention, while 2denotes a rectangular or square blade which is formed as from a certainheight of the central body 1 and is positioned along a longitudinalmid-plane of said central body. This blade 2 comprises an end part 102which extends at the bottom beyond the end of the central body 1 with asmaller cross-section and is provided at the end with a transverse tip202 which has edges which are suitably chamfered in order to avoidundesirable damage to the patient's bone. Said rectangular blade 2 andsaid central body 1 thus give the present implant a substantiallywedge-like form. A series of transverse teeth 101 located on twodiametrically opposite surfaces of said central body 1—in this case onthe front surface and on the rear surface thereof—are formed along theentire surface of the central body 1 (see also FIG. 3 of theaccompanying drawings). Transverse grooves 301 of suitable size areformed between each pair of adjacent front and rear transverse teeth101: the grooves with a greater depth ensure a high primary stability,reducing the lateral and vertical micro-movements of the implant, whilethe grooves with a smaller depth ensure a high secondary stability,increasing the surface area of the implant. The top part of the centralbody 1 with a larger cross-section is provided with two diametricallyopposite flattened surfaces substantially in the form of an arc of anellipse, namely (see also FIG. 2 of the accompanying drawings) the frontflattened surface 201 and the rear flattened surface 501. The transverseteeth 101 are also formed in these flattened surfaces 201 and 501 andextend so as to be bounded by these flattened surfaces 201 and 501. Athread 401 comprising a plurality of small teeth is formed in the toppart of the central body 1, corresponding to the neck of the endosseouspart. Transverse teeth 302 which extend over the entire width of thisblade are also formed on the front and rear surfaces of the end part 102of the blade 2. The latter series of teeth 302 formed in the vicinity ofthe tip 202 of the blade 2 may also not be provided. A series of teeth402 separated by suitable grooves 502 with a substantially semi-circularshape are formed along the entire length of each of the longitudinaledges of the blade 2. These longitudinal edges of the blade 2 providedwith teeth 402 are positioned symmetrically with respect to the centralbody 1. The end part 102 of the blade also has, formed therein, one ormore through-holes 602, for example two through-holes, designed toallow, once the implant has been inserted into the patient's bone, morerapid vascularization and also optimum grip and integration within thebone.

The top end of the central body 1 with a larger cross-section has,formed therein, a connection seat 701 with a small angle A of conicitywhich may vary from about 1° to about 2° with respect to a genericcylindrical hole. A threaded cylindrical hole 801 is provided at thebottom of this connection seat 701: a stump pin for the present implantwill be engaged inside this seat 701 and this threaded cylindrical hole801. Owing to this small angle A of conicity a series of advantages maybe obtained: the so-called cold welding together of the seat 701 of theimplant and the stump pin which is to be inserted inside this seat, witha consequent and advantageous reduction in the internal space andtherefore a reduction in the spaces which may favour the proliferationof bacteria: and a horizontal coronal zone which is useful as a zone forsupporting the connecting tissues and bone.

The central body 1 and the blade 2 are preferably made of atitanium/aluminium/vanadium alloy, Ti—Al₆—V₄ (pure titanium or alloy oftitanium, tantalum, zirconia, ceramic material, or using other materialswhich are biocompatible and/or suitable for bone grafts) and the sitewhere the implant must be inserted is prepared preferably using apiezoelectric surgical technique and technology, i.e. “piezosurgery”,which is known per se, or using other technologies such as sonictechnology, laser technology or manual instruments such as blades orosteotomes. The front and rear teeth 101 and 302 project from thesurface of the conical body 1 and the blade 2 in the manner of sawteeth, namely are provided with inclined surfaces able to facilitateinsertion of the implant in the patient's bone and, in combination withthe grooves 301, ensure optimum anchoring and stability once the implanthas been inserted in the patient's bone. These teeth may have differentforms depending on different constructional versions.

According to the embodiment of the invention described above, theimplant formed by the central body 1 and the blade 2 and having asubstantially wedge-like shape may advantageously be fixed also in zoneswhere the patient's bone has a small thickness; this wedge-like formallows expansion of both the cortical and the spongy bone, takingadvantage of its viscoelastic properties. Therefore, the vestibularcortical bone may also expand with respect to the lingual/palatine boneafter performing on the patient's bone a thin osteotomy or a cut,providing a thin site inside which this implant is introduced. From abiological point of view the difference between the conventionalimplants and the present implant is notable since, in conventionalimplants, it is required to remove from the bone crest all the volumenecessary for insertion of the implant using suitable milling cutters;in the present implant only a thin cut, which may vary for example from0.1 mm to 1 mm, is required, therefore maintaining a sufficientthickness of the vestibular and palatal bone walls even in the presenceof thin bone crests.

Suitably shaped recesses 901 which improve further the stability of theimplant are formed along the front and rear surface of the central body1—see FIGS. 4 and 5 in which identical parts are indicated by the samenumbers used for the previous description. This central body 1 alsocomprises at the top the connection seat 701 comprising the threadedhole 801 for insertion of a stump pin for the present implant. In thisembodiment also a series of teeth 402 separated by suitable grooves 502with a substantially semicircular shape are formed along the wholelength of each of the longitudinal edges of the blade 2. Theselongitudinal edges of the blade 2 provided with teeth 402 are positionedsymmetrically with respect to the central body 1. A series of suitablyshaped recesses 702 are formed on the front surface and on the rearsurface of the blade 2, opposite said teeth 402 or said grooves 502. Theend part 102 of the blade is also provided with a single through-hole602 designed to allow, as mentioned above and once the implant has beeninserted in the patient's bone, a more rapid vascularization and alsooptimum grip and integration within the bone.

A projecting longitudinal rib 3 designed to guide correctly the implantduring its insertion inside the patient's bone is formed on each of thefront and rear surfaces of said central body 1 and said blade 2,preferably in a central position. Each of these longitudinal ribs 3helps facilitate insertion of the implant in the bone in such a way asto avoid damage to the bone itself and maintain constantly thepredefined axis for insertion of the implant. These ribs 3 moreoverincrease the primary stability of the implant, allowing perfectanchoring which prevents possible transverse movements.

Preferably these longitudinal ribs 3 are identical and positioned so asto be diametrically opposite with respect to the main body 1 and to theblade 2, but in other embodiments they may also be single or asymmetricdepending on the anatomical or biomechanical requirements. Each of theseribs 3 has a top end with a greater thickness in the top part of implantand a bottom end for connection to the blade 2. The thickness of the rib3 therefore decreases from this top end towards this bottom end wherethe rib 3 is connected to the blade 2. According to other embodiments,these ribs may have thicknesses, forms and dimensions which arevariable, continuous or with a sawtooth shape, in various constructionalforms which are adapted to the anatomical variations of the availablebone both with regard to height and thickness and in terms of densityand quality.

The central body 1 and the blade 2 are designed so as to give thepresent implant a substantially blade-like form; in fact the angle ofconicity B of the implant is in the region of 1° or less.

The blade-like form of this second embodiment of the present implant,which is therefore advantageously designed with a small thickness,allows the same to be used in a simple and efficient manner in bonezones with a very small bone volume or in zones with atrophic crests.The simplicity with which the present implant can be inserted alsoreduces advantageously the surgery time for installation of the implant,the possibility of infections and any undesirable damage to the bone.

The present implant is advantageously compatible with the stump pins ofthe most well-known implant manufacturers in the sector (31, SwissPlus,Branemark, Straumann, Zimmer) owing to an intermediate connection(between implant and stump) which may, in some cases, be separate fromthe implant and therefore be able to be added thereto during stagesfollowing that of implant insertion and, in other cases, may evenalready form part of the implant itself (thus forming a single piece),thereby creating a complete assembly which can already be combined withthe other implant systems without further adaptation. This implant isalso provided with an aesthetic finish on the neck and in the partemerging from the gums.

Moreover, despite the fact that the present implant has dimensionalcharacteristics such that it may be inserted in thin crests, it has anexcellent strength and standard-size surface area (bone contact area)and prosthetic connection, unlike the known implants where, following areduction in the dimensions and in particular the diameter, both thebone contact area and the strength and dimensions of the prostheticconnection are reduced. CLAIMS LISTING

1. Dental implant, characterized in that it comprises a central bodywith a substantially conical or frustoconical shape and having,extending from the end with a larger cross-section, a connection seatable to receive a stump pin, said central body being provided with ablade positioned in a longitudinal mid-plane of said central body andhaving a length such as to protrude beyond the end of said central bodywhich has a smaller cross-section, said central body and said bladebeing able to give the implant a substantially wedge-like form havingthe function of expanding the bone during insertion.
 2. Dental implantaccording to claim 1, characterized in that the longitudinal edges ofthe blade are positioned symmetrically with respect to said centralbody.
 3. Dental implant according to claim 1, characterized in that saidblade comprises a transverse end tip.
 4. Dental implant according toclaim 1, characterized in that said blade has a square or rectangularshape and has, along its longitudinal edges, a series of teeth which areseparated by suitable grooves.
 5. Dental implant according to claim 1,characterized in that at least two diametrically opposite walls of saidcentral body are provided with a series of transverse teeth betweenwhich suitable grooves are formed.
 6. Dental implant according to claim1, characterized in that transverse teeth are formed at least on thediametrically opposite walls of the blade.
 7. Dental implant accordingto claim 5, characterized in that: said blade has a square orrectangular shape and has, along its longitudinal edges, a series ofteeth which are separated by suitable grooves; and said transverse teethformed on two diametrically opposite walls of the central body and theblade have an inclined surface so as to facilitate insertion of theimplant in the patient's bone and at the same time be anchored to thepatient's bone once the implant has been inserted.
 8. Dental implantaccording to claim 1, characterized in that said central body compriseson the top part two diametrically opposite flattened surfaces in whichtransverse teeth re positioned.
 9. Dental implant according to claim 7,characterized in that said flattened surfaces have a semicircular orsemi-elliptical form and bound the transverse teeth formed therein. 10.Dental implant according to claim 1, characterized in that said bladecomprises an end part in which one or more through-holes are formed. 11.Dental implant according to claim 1, characterized in that a threadedcylindrical hole is provided at the bottom of said connection seat andtherefore towards the inside of the central body.
 12. Dental implantaccording to claim 1, characterized in that said connection seat has acertain angle of conicity with respect to a generic cylindrical form.13. Dental implant according to claim 1, characterized in that the toppart of the central body is provided with a thread comprising a seriesof small teeth.
 14. Dental implant according to claim 1, characterizedin that said central body and said blade are made preferably using atitanium/aluminium/vanadium alloy or other materials which arebiocompatible or suitable for bone grafts.
 15. Dental implant accordingto claim 1, characterized in that it comprises, at least on the front orrear surface of said central body and said blade, at least onelongitudinal guide rib projecting from said surface.
 16. Dental implantaccording to claim 1, characterized in that said central body and saidblade have an angle of conicity of at least about 1° or less so as togive the implant a substantially blade-like form.
 17. Dental implantaccording to claim 1, characterized in that it comprises two ribspositioned on the front and rear surfaces of said main body and saidblade so as to be diametrically opposite each other.
 18. Dental implantaccording to claim 1, characterized in that said longitudinal rib ispositioned centrally in said front or rear surface of said main body andsaid blade.
 19. Dental implant according to claim 1, characterized inthat said rib has a top end with a greater thickness in the top part ofthe implant and a bottom end for connection to the blade, the thicknessof said rib decreasing from said top end towards said bottom end wherethe rib is connected to the blade.
 20. Dental implant according to claim1, characterized in that suitably shaped recesses are formed in saidmain body and/or in said blade.
 21. Dental implant according to claim 1which in the part emerging from the gums and the bone has a white,yellow or pink coloured aesthetic finish/coating so as to blend inbetter with the colour of the gums and/or the tooth.